Storage Controller Garbage Collection Using Replicated Data Skipping
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Solution Overview
Problem
Current data storage devices face inefficiencies in garbage collection, leading to increased write amplification, reduced throughput, and increased wear on memory blocks due to the need to copy and erase data, which can result in blocks becoming unavailable for use.
Innovation Solution
Implementing a method where data storage devices mark replicated data during writes and use a cost function based on the number of free and replicated pages to determine which blocks to copy during garbage collection, thereby avoiding the copying of replicated data and reducing write amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional garbage collection copies all valid data blocks during garbage collection, then data integrity is maintained, but write amplification increases and memory block lifespan decreases
Solution Approach 1:
The patent applies local quality by differentiating between replicated data and non-replicated data within the storage system. Replicated data blocks are identified through specific indicators (e.g., reserved bits in LBA structures) and treated differently during garbage collection - they are skipped and not copied, while non-replicated data blocks continue to be copied normally. This localized differentiation reduces write amplification for replicated data while maintaining data integrity for non-replicated data.
2Reliability
If traditional garbage collection copies all valid data blocks during garbage collection, then data availability is maintained, but the number of write-erase cycles increases
Solution Approach 1:
The patent implements local quality by identifying replicated data blocks through specific indicators (such as reserved bits in logical block address structures) and applying a different garbage collection policy to these blocks. Replicated data blocks are skipped during garbage collection operations, reducing the number of write-erase cycles they undergo, while non-replicated data blocks continue to receive full garbage collection protection. This extends memory block lifespan by reducing unnecessary write operations on replicated data.
3Productivity
If replicated data is not copied during garbage collection, then write amplification is reduced, but data availability may be compromised
Solution Approach 1:
The patent implements feedback mechanisms where the storage system continuously tracks which data blocks are replicated and maintains metadata about their replication status. During garbage collection operations, this feedback information is used to identify and skip replicated data blocks. The system also provides notifications to host systems about the status of replicated data, ensuring data availability is maintained through coordinated management between storage and host systems.
4Device complexity
If traditional garbage collection operates without distinguishing data types, then implementation complexity is low, but system performance deteriorates
Solution Approach 1:
The patent applies preliminary action by marking and identifying replicated data blocks at the time of data writing, using indicators such as reserved bits in logical block address structures or metadata tags. This preliminary identification eliminates the need for complex runtime analysis during garbage collection, as the storage system can simply follow the pre-marked indicators to identify which blocks to skip. This approach maintains low implementation complexity while significantly improving system throughput during garbage collection operations.
Data Source
AI summary
A method includes determining which of a plurality of blocks of data in a data storage device having a plurality of memory devices to copy during garbage collection using a cost function based on a number of free pages and a number of replicated pages in each of the blocks, where the replicated pages include replicated data that is a copy of data stored in another storage device and determining not to copy one or more of the blocks of data during garbage collection based on the cost function.